1. Field of the Invention
The present general inventive concept relates to an image forming apparatus and a paper feeding method used with the same, and more particularly, to an image forming apparatus that controls an arrangement speed according to paper thickness in order to prevent overall problems occurring during a paper arrangement process, and a paper feeding method used with the image forming apparatus.
2. Description of the Related Art
FIG. 1 is a view of an ink-jet printer as an example of a conventional image forming apparatus. Referring to FIG. 1, the image forming apparatus includes a paper feeding unit 10 that stores a plurality of papers P (or other recording media) and a pick-up roller 11 to pick up the papers P sheet by sheet, which is disposed above the paper feeding unit 10. A paper arrangement unit 30, a feeding roller 41, and a printing unit 50 are disposed on a transfer path of the papers P transferred by the pick-up roller 11.
The paper arrangement unit 30 includes a driving roller 31 and a pinch roller 35 which are pressed in contact with each other to form a nip N′. The driving roller 31 is connected with a driving motor 39 supplying a rotation driving force. An electronic clutch 38 is disposed between the driving roller 31 and the driving motor 39 to intermittently connect or disconnect the driving roller 31 to or from the driving motor 35. A pinch spring 37 is placed at another side of the pinch roller 35. The pinch roller 35 rotates in conjunction with the driving roller 31 while being pressed thereto by the pinch spring 37. When a position sensor 33 disposed close to the paper arrangement unit 30 detects the paper P, the driving roller 31 does not rotate immediately, but instead waits for a predetermined period of time to prevent paper skewing when the front end Pt of the paper P moves diagonally. In the paper arrangement unit 30, when a leading portion of the paper P is transferred, the paper P is pushed back while being stuck between the two rollers 31 and 35. When the lagging portion of the paper P is moved, the driving roller 31 rotates so as to align the paper P.
The paper P is pushed by a feeding force while passing between the driving roller 31 and the pinch roller 35 and is transferred towards the feeding roller 41. After the paper P is transferred to the feeding roller 41, the paper P enters between the feeding roller 41 and a friction roller 43 and then between an ink cartridge 51 and a paper guide 59. The ink cartridge 51 discharges ink droplets on the transferring paper P to form a predetermined image. The printed paper P is then discharged out of the inkjet printer between a star wheel 61 and a discharge roller 63, which both rotate while being pressed against each other, and is then the printed paper is loaded on an out-feed tray 71.
Examples of papers which are commonly used for an image forming apparatus such as an ink-jet printer include a plain paper, an ink-jet paper, and a photo paper. Since these types of papers are made of a laminated sheet including a chemical coating layer, the ink-jet paper and the photo paper are thicker than plain paper. Conventionally, an arrangement operation is performed under the same conditions regardless of a type of a paper supplied to a paper arrangement unit. Accordingly, when a thin plain paper is used, the paper creases in the paper arrangement process due to a lack of rigidity. In addition, when a relatively thick ink-jet paper or a photo paper is used, although the arrangement operation is performed, the paper is supplied to a feeding roller in a skewed position, resulting in a paper jam. Also, even when no paper jam occurs, there still is a problem in that ink discharged from an ink cartridge escapes from the paper, causing poor printing.